Reaction determination and control especially for the production of hydrate from quicklime



C. REACTION DETERMINATION AND CONTROL ESPECIALLY FOR THE PRODUCTION OF HYDRATE FROM QUICK LIME Filed Oct. 9, 1928 March 17, 1931. R REX 1,796,396

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Patented Mar. 17, 1931 UNITE stares "oLARENo'E n. REX, or TOLEDO, 01110 FOR THE PRODUCTION Application filed-October 9, 1928. Serial-No. 311,404.

This invention relates to control ofreactions. i z I This invention hasutility when incorporated in determining factors of temperature, time, and bulk as to quantities of reactants of water and quick lime in the production of hydrate. n 1

Referring to the drawing: i The figure is a view of a time temperature chart as produced froincontinuous checking of the temperature of the reaction.

Beferrmg to the chart and taking such as the inner of the pair of heavy lines or circles as being the boiling pointof water, say 100 C. and the outer heavyhline as 110 0., these lines, in the experience of applicant with the hydration of lime, even of high magnesium content, are lines within which itis desirable to maintain the temperature durs ing the reaction for uniformity of product as a hydrate, suitable for wall finish purposes. In the production of hydrates hereunder, thest0ne from the quarry is desirably sorted to let-pass stone which goes through a sixinch screen, the coarser stone of seven inch or thereoverv being retained for charging "the kiln. M

f In this burning in a kilnsay of. the shaft type, the temperature is desirably. kept in the kiln within a range of 850 C. to 950 C. with a burningtime of say three and onehalfhours approximately. The shaft kiln of thisigeneral type has the eye 'for. receiving thehigh temperature ases from the furnace spacedupward from the bottom of the kiln so that therebelow is acooling chamber into which the burned limestone from the kiln passes andin which the temperature drop may be to the region of125. G. The quick limeas discharged from this cooling chamber of the kiln onto the floor or conveyor'may be sorted as to any limestone of an objectionable character, as so-ca-lled corewhich is under-burned, or any which might'be overburned. This limestone as conducted from the kiln and still hot, say of atemperature approximating 90 C- is ground say in a mill of the Bonnet type to a finenessof one-eighth inch and under. Inthis handling as an ap- 50 proximately continuous process, the limestone as still warm and in theregion of 7 0? C. and'prefe'rablyf under 80 C., is ready to be charged into the hydrators. f

In the operations hereunder,1two hydrators ofthe Clyde type maybeoperated, with the rate of operation approximating four batches per hour. Accordingly, there may be an accumulation in a hopper for the hydrator say one ton of this hot ground quick lime. A hopper ortankfor wateris also charged with a'quantity of water of a temperatrirdbelowthat of the quick lime but desirably above normalatmospheric temperature. The-hydrator'is running as the bin is dumped and the water'is sprayed onthis hot quick lime. A gage bar is located in the hydrator,as well as a temperature indicating instrument located just down inthe mass say in the rear of a plow for continuously recording the temperature condition in the mass as undergoing this exothermic reaction 1! The I temperature 01? the batch at once jumps, in-the desirable handling'hereunder, to the boiling point of the water and approximates aflconstant within a degree or so of such region, usually slightly above, and this temperature as thus held is one lasting until the determined bulk as shown by the gage bar on thefhydratoris reached. Then the 'hydrator is dumped with the-material descent to storage or sacked as may be desired, after a-separation has occurredfor eliminating" impurities orimproperly hydrated material. This separation maybe eifected by a Raymond mill. The improperly hydrated material may be returned to th 'charging bm v H v In the instance of the operations here?- under, the temperature instrument is effective not only for speeding up the operation in th'at the timing schedule is an' automatic check uponthe operator, having been effective for increasingthe output upward of 30% per-man power and hydrator, butthere is the great importance of character of output with a visual showing of conditions to be avoided and warranting even rejection of the product for finishing hydrate.

V In theinstance herein, the hydration. may

PATENT, OFFICE be taken as charge going on at 8.45 a. m. the hot lime with the water supplied is approximately C. The temperature at once jumped to C. and there the temperature was held for a minute or so and jumped again to above C. showing there was lack of water to hold the temperature down. The drop indicates addition of water and the completion of the hydration with dumping at 9.05 a. m.

In the .re-charging the temperature of the burned limestone was high and so close to the boiling point of water that while the water volume was approximately sufficient, the temperature of the reaction drove oif this water excessively and the temperature jumped above 140 C. This objectionable rise in temperature was checked by the addition of water down to approximately 105 C. In the re-charging for the batch at 9.40 a. m. a lower temperature for the burned limestone and water checked the rise of reaction to slightly over 120 0., but this was objectionably excessive and would indicate improper quantity of water supplied during the reaction. The later portion of the reaction at approximately 105 C. completed the treatment.

The charge at 10.25 a. 111. shows an objectionable condition in the initial rise up to in the region of 180 C. with the drop back to about 105 C. as the desired temperature for hydration. However, this desired temperature of hydration was evidently with excess of water in pulling down .at the 10.30 a. m. then high peak point, so that at 10.55 a. m. there was a drop below 100 C. which prompted the attendant to add raw lime, thus jumping the temperature up to about C. and then the batch was dumped indicating an improper treatment.

This course was repeated in the hydration thereafter charged at 11.20 a. m. which had the drop below the boiling point of water at 11.47 a. m. with raw lime added to make the jump in temperature to the region of 130 C. at 11.55 a. m. This dropped back for the proper hydration between 12.00 M. and 12.15 p. m. The charge at 12.25 p. In. due to lack of moisture, went but slightly above the 110 C. line, and more water dropped it back to a desirable hydrating temperature of 100 C. However, -evidently :the operator felt the proportion of water in excess, and dumped in some raw quick lime at 12.50 p. 111. Then realizing that the rise in temperature had thrown off :the hydration, such was dumped.

The charge at 1.00 p. m. came up to the hydration temperature and with slight fluctuation and slight rise shows that the water content was not sufficient to hold the temperature uniform during the hydration.

.. However, the water content was sufficiently in excess to keep the temperature from building up objectionably as the showing for this was within 105 C. and likewise for the next batch as a little better. However, the batch charged at 1.45 p. m. was spasmodic and jumped up showing lack of water in the batch. This experience evidently discom fitted the operator.

The charge 2.20 p. m. which went up to the boiling point of water very nicely, was fine at this stage. Even the disturbance in jumping up to 105 C. was not objectionable, but the dropping back while not below 100 C.

evidently exhibited a too wet condition, and

the addition of quick lime shot the temperature up to 110 C. at 3.15 p. m. and-here again dumping followed. There was the charge at 3.30 with insufficient water so that the temperature with slow reaction on account of too much lime for the water worked up to above C. at 3.50 p. m.

The conditions of too much lime for the water content are shown in the charges at 3.55 p. m., 4.20 p. m., and 4.45 p. m., this latter showing so much excess of lime that hydration temperature jumped to approximately 120 C, while the lack of flatness for curve constant temperature in the hydration interval, and with such rising, indicates an excess of lime or rather an insufficient excess of water.

The hydrations from 5.10 p. m. to 7.00 p. m. inclusive are of an acceptable character. These features of lack of flatness for constant temperature during the hydration process show up slowness in reaction due to the character of the raw stone or the condition confronted during the burning. TlllS slow reacting character of the quick lime promotes the rise in temperature as the reaction progresses, but this is a gradual rise as the chart shows.

However, it is evident that as the raw material supply is of higher temperature, as at 11.15 p. m. there is a pushing up of this maximum hydration temperature as shown at 11.30 p. m. The charge at 11.35 p. m. was clearly one involving too much water for while the temperature of the reaction was as desired between 11.85 p. m. and 11.45 p. m., the drop thereafter is a clear indication of excess of water, and the rise at 12.15 a. m. shows the addition of raw material to take up the excess of such water.

From these freak conditions, there is following record of charges as more properly controlled. The interval of hydration of the charge at 12.35 a. m. was excessive, but the temperature was well carried even though the reaction may have been slow in getting the material to the bulk of the gage bar. However, with the charge at 1.80 a. m. and thereafter, there is a maintained condition of uniformity with the chart accurately showing that upon dumping at 5.00 a. m. the

operator was off until after 6.00 a. m. when the continuation of the charges was had with approximately fifteen minute hydration intervals in the running of the hydrations to approximately a little better than two per hour. These charts permit accurate diagnosis ofconditions for a given lime. It is thus possible for the superintendent to establish a set of bulk and time conditions which an ordinary laborer may follow for bringing about in succession different treatments of like character. Furthermore, as the chart discloses any departure it is a call for cor rection by the superintendent if involving problems with which the laborer attendant may not be familiar.

What is claimed and it is desired to secure by Letters Patent is:

1. The method of producing a lime hydrate comprising mixing a measured quantity of water with a measured quantity of quick lime, determining the volume of said water and the rate of supplying of the Water to the lime together with mixing to approximate a constant temperature during the reaction, and checking the reaction as complete by the predetermined increase in volume in establishing a production condition, and obtaining plant output by duplicating in succession said production condition.

2. The method of producing a lime hydrate comprising agitating a measured quantity of quick lime, spraying water therein, determining the quantity of said water for holding the temperature during the reaction at an approximate constant, bringing the mass up to a determined volume, and then removing such mass as the finished hydrate in completing a unit of performance for a repetition in approximate identity.

In witness whereof I aflix my signature.

CLARENCE R. REX. 

